This invention relates to an improved covered highway structure for use in heavily urbanized areas to reduce traffic noise and air pollution and, more particularly, to a tunnel structure including means for permitting easy and quick access to tunnel interior when accidents such as car collisions or fires occur.
A depressed highway is often constructed in heavily urbanized areas for carrying heavy, noisy traffic. It is formed by cutting a channel into the ground and constructing a highway track along the bottom of the channel. However, the construction of such a depressed highway is usually quite expensive because of excavations involved.
To avoid such limitations of the prior art, it has been proposed to provide a wind tunnel structure which encloses a highway at the ground surface, as disclosed in Japanese Laid Open Patent Application No. 2001-200511. The proposed tunnel structure includes a wind tunnel built over a highway and a slanting wind deflector slab provided at the exit end of the tunnel. The tunnel is ventilated by the piston action of the moving traffic, assisted by fans or blowers, to push air from the entrance toward the exit of the tunnel. The exiting air is deflected upwardly by the wind deflector slab for increased diffusion of air pollutants such as carbon monoxide and traffic noise.
However, it has been found that a covered highway sometimes causes a significant problem. The covered highway has no side entrances in the intermediate portion thereof that permit easy and quick access to the interior when accidents such as car collisions or fires occur. Also, the covered highway structure disclosed in the Japanese laid open application does not have vent openings either. It will be understood that the absence of openings such as side entrances and vent openings will inevitably cause difficulties to maintenance personnel in repairing road surfaces and tunnel inner walls because their operation is hampered by rather strong wind generated by the piston action of the moving traffic.
The present invention provides an improved covered highway structure which substantially eliminates or reduces the above described problems. The highway structure includes openings such as side entrances and/or vent openings provided in the tunnel roof. The side entrances are normally closed to prevent ventilation of the tunnel therethrough but can be opened to permit entry of fire engines and ambulances into tunnel interior in the event of accidents such as car collisions or fires. A plurality of such side entrances may be provided at equal intervals along the length of the tunnel, although the present invention is not limited to any specific location and spacing of the side entrances. The vent openings are also normally closed but can be opened to ease the wind pressure problem experienced by maintenance personnel during repair work.